Field of the Invention
The present invention relates to a sheet storing apparatus, a sheet feeding apparatus, and an image forming apparatus.
Description of the Related Art
An image forming apparatus such as a copier, a printer, and a facsimile machine of a sort of feeding a sheet to an image forming unit from a sheet feeding apparatus to form an image on the sheet is being widely used today. In general, the sheet feeding apparatus includes a sheet feed cassette, i.e., a sheet storing apparatus, removably attached to an apparatus body and feeding the sheet stored in the sheet feed cassette to the image forming unit by a sheet feed roller.
Some of the sheet feed cassettes used in the sheet feeding apparatus includes a sheet supporting plate liftably provided to stack a sheet and to press the sheet against a sheet feed roller for example. The sheet feed cassette is provided with a rear end regulating portion configured to regulate a position of a rear end in a sheet feed direction of the sheet (referred to as a ‘rear end’ hereinafter) stored in the sheet feed cassette which is configured to be able to store different size sheets. The sheet feed cassette is also provided with a pair of side regulating members configured to regulate side end positions in a direction orthogonal to the sheet feed direction (referred to as a ‘width direction’ hereinafter) of the sheet stored in the sheet feed cassette.
Such sheet feed cassette is configured to regulate the rear end of the sheet by the rear end regulating portion while regulating the side ends of the sheet by the pair of side regulating members to regulate a front end position of the sheet always at a predetermined position. This arrangement makes it possible to feed the sheet from a same position and to feed the sheet stably when the sheet feed cassette is stored in an apparatus body.
In the conventional sheet feed cassette, there is a case when the sheet stacked on the sheet supporting plate floats above an upper end of the side regulating portion when the sheet supporting plate rises. The sheet is conveyed askew if the sheet is fed in this condition. Then, in order to regulate the sheet from floating up as described above, a tab-shaped member is provided at an upper end of a unit body regulating a side end of a sheet to press the sheet from above and to regulate the sheet from getting over the upper end of the unit body as disclosed in Japanese Patent Application Laid-open No. 2011-57450.
As another arrangement, a curl presser portion is turnably attached to a front end of a regulating surface of a regulating member configured to regulate a side end of a sheet to regulate a curled part of the sheet from getting over the upper end of the regulating member by the curl presser portion as disclosed in Japanese Patent Laid-open No. 2001-88970 for example. The curl presser portion presses the curled part at an end of the stacked sheet by being held at a position approximately at a right angle with respect to the regulating surface by an urging member.
By the way, in the case of the arrangement of pressing the sheet by the tab-shaped member, it is necessary to store the sheet while avoiding the tab-shaped member so as not to damage the sheet in storing the sheet because the tab-shaped member is fixed to the unit body. Thus, storability of the sheet deteriorates.
Meanwhile, in the case of the arrangement of pressing the sheet by the curl presser portion, the storability of the sheet does not deteriorate in storing the sheet because the curl presser portion turns downward by resisting against an urging force of the urging member by being pressed from above by the stored sheet. However, this arrangement requires a plurality of components, thus leading to an increase of cost and to deterioration of assemblability.